On Thu, Feb 27, 2020 at 10:50:45AM +1100, Stephen Rothwell wrote:
> Hi all,
>
> On Fri, 21 Feb 2020 13:17:07 -0800 Arjun Roy <arjunroy.kdev@xxxxxxxxx> wrote:
> >
> > From: Arjun Roy <arjunroy@xxxxxxxxxx>
> >
> > pte_index() on platforms other than sparc return a numerical index.
> > On sparc, it returns a pte_t*. This presents an issue for
> > vm_insert_pages(), which relies on pte_index() to find the offset for
> > a pte within a pmd, for batched inserts.
> >
> > This patch:
> > 1. Modifies pte_index() for sparc to return a numerical index, like
> > other platforms,
> > 2. Defines pte_entry() for sparc which returns a pte_t*
> > (as pte_index() used to),
> > 3. Converts existing sparc callers for pte_index() to use pte_entry().
> >
> > Signed-off-by: Arjun Roy <arjunroy@xxxxxxxxxx>
> >
> > ---
> > arch/sparc/include/asm/pgtable_64.h | 11 ++++++-----
> > 1 file changed, 6 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
> > index 65494c3a420e..851ed0f99159 100644
> > --- a/arch/sparc/include/asm/pgtable_64.h
> > +++ b/arch/sparc/include/asm/pgtable_64.h
> > @@ -907,11 +907,12 @@ static inline unsigned long pud_pfn(pud_t pud)
> > (((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1)))
> >
> > /* Find an entry in the third-level page table.. */
> > -#define pte_index(dir, address) \
> > - ((pte_t *) __pmd_page(*(dir)) + \
> > - ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)))
> > -#define pte_offset_kernel pte_index
> > -#define pte_offset_map pte_index
> > +#define pte_index(address) \
> > + ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
> > +#define pte_entry(dir, address) \
> > + ((pte_t *) __pmd_page(*(dir)) + pte_index(address))
> > +#define pte_offset_kernel pte_entry
> > +#define pte_offset_map pte_entry
> > #define pte_unmap(pte) do { } while (0)
> >
> > /* We cannot include <linux/mm_types.h> at this point yet: */
> > --
> > 2.25.0.265.gbab2e86ba0-goog
>
> I have applied the following patch to the akpm tree today (just ahead
> of "mm/memory.c: add vm_insert_pages()") - this includes my suggested
> changes.
>
> From: Arjun Roy <arjunroy@xxxxxxxxxx>
> Date: Fri, 21 Feb 2020 13:17:07 -0800
> Subject: [PATCH] mm: Bring sparc pte_index() semantics inline with other platforms.
>
> pte_index() on platforms other than sparc return a numerical index.
> On sparc, it returns a pte_t*. This presents an issue for
> vm_insert_pages(), which relies on pte_index() to find the offset for
> a pte within a pmd, for batched inserts.
>
> This patch:
> 1. Modifies pte_index() for sparc to return a numerical index, like
> other platforms,
> 2. Defines pte_entry() for sparc which returns a pte_t*
> (as pte_index() used to),
> 3. Converts existing sparc callers for pte_index() to use pte_entry().
>
> sfr: removed pte_entry and just directly modified pte_offset_kernel instead
>
> Signed-off-by: Arjun Roy <arjunroy@xxxxxxxxxx>
> Signed-off-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
FWIW: Reviewed-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> ---
> arch/sparc/include/asm/pgtable_64.h | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
> index 65494c3a420e..930ea3c12739 100644
> --- a/arch/sparc/include/asm/pgtable_64.h
> +++ b/arch/sparc/include/asm/pgtable_64.h
> @@ -907,11 +907,11 @@ static inline unsigned long pud_pfn(pud_t pud)
> (((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1)))
>
> /* Find an entry in the third-level page table.. */
> -#define pte_index(dir, address) \
> - ((pte_t *) __pmd_page(*(dir)) + \
> - ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)))
> -#define pte_offset_kernel pte_index
> -#define pte_offset_map pte_index
> +#define pte_index(address) \
> + ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
> +#define pte_offset_kernel(dir, address) \
> + ((pte_t *) __pmd_page(*(dir)) + pte_index(address))
> +#define pte_offset_map(dir, address) pte_offset_kernel((dir), (address))
> #define pte_unmap(pte) do { } while (0)
>
> /* We cannot include <linux/mm_types.h> at this point yet: */
> --
> 2.25.1
>
> --
> Cheers,
> Stephen Rothwell
--
Sincerely yours,
Mike.
